1. Field of the Invention
The present invention relates to a variable focus lens, and in particular, a variable focus lens that uses a liquid.
2. Description of the Related Art
Conventionally, a variable focus lens is known that can vary its refractive power by controlling the shape of an interface of a liquid by using the electrowetting phenomenon. Here, the variable focus lens disclosed in Japanese Patent No. 4154858 changes refractive power by controlling the shape of an interface of two types of liquid by using the electrowetting phenomenon. In addition, a zoom lens that is disclosed in Japanese Patent Laid-Open No. 2006-504132 carries out zooming by controlling the shape at least at two interfaces. Furthermore, a variable focus lens disclosed in Japanese Patent Laid-Open No. 2007-518133 corrects chromatic aberration by restricting the refractive index and the Abbe number to a certain range in a variable focus lens that changes refractive power by controlling the shape of one interface.
However, in the variable focus lens of Japanese Patent No. 4154858, there is only one interface of the liquid that changes the refractive power, and thus, correcting chromatic aberration is difficult. In addition, the zoom lens in Japanese Patent Laid-Open No. 2006-504132 does not disclose conditions in which the chromatic aberration is corrected when the shapes of a plurality of interfaces are controlled. Furthermore, the variable focus lens of Japanese Patent Laid-Open No. 2007-518133 is a variable focus lens in which the shape of one interface is changed, and thus, in order to correct chromatic aberration, a liquid that satisfies special conditions must be selected, and the range of the selection of liquids is thereby limited.